In this presidential election, it's common to see candidates hurling verbal spit balls at each other. And this week one came from an unexpected source, Supreme Court Justice Ruth Bader Ginsburg, and it was returned by an expected source, presumptive Republican nominee Donald Trump. Joining us to talk about this flap is NPR legal affairs correspondent Nina Totenberg. Hiya.

NINA TOTENBERG, BYLINE: Hi.

SIEGEL: Let's start with Justice Ginsburg and what she said. She said she couldn't imagine what the country would be like with Donald Trump as president and that her late husband would say that it's time to move to New Zealand.

TOTENBERG: Well, she started off with an interview in The New York Times where she said that, you know, everything would be up for grabs if Trump were elected and that she was very worried about it. And then she doubled down in an interview with CNN where she called him a faker who has no consistency about him. And she said the press has unaccountably allowed him to get away with not releasing his tax returns when every other candidate has done so.

Now, it's not that modern-day justices haven't been overheard making comments about presidential candidates, but Ginsberg is the first I'm aware of in modern times, anyway, to publicly criticize a presidential candidate.

SIEGEL: Very intentionally, obviously, the way you're describing it.

TOTENBERG: And she doesn't give these interviews without malice of forethought.

SIEGEL: After the New Zealand line, Trump spat back at Ginsburg. What did he say about her?

TOTENBERG: He tweeted out a message saying that she has embarrassed all by making very dumb political statements about me and adding that her mind is shot and that she should resign.

SIEGEL: Let me ask you about that last part. You've known Ruth Bader Ginsburg for a long time. Is her mind shot, and is she going to resign?

TOTENBERG: Well, as Josh Earnest at the White House put it today, she didn't earn the nickname the Notorious RBG for nothing.

SIEGEL: (Laughter).

TOTENBERG: She can be blunt, but her mind is not shot. I would give anything to have all the marbles in my head that she has in hers, and anyone who watches her on the bench or reads her work knows that. And she's probably not going to resign, at least not now. But having said that, she's created quite a stir and caught a lot of criticism on this and not just from conservative critics but from liberals, too.

SIEGEL: Well, did she in fact cross a line here?

TOTENBERG: Well, yes and no. Remember that one of the most admired Supreme Court justices, Charles Evans Hughes, resigned from the Court in 1910 to run for president, lost and, in 1930, was appointed chief justice. And justices have long had private political friendships and even alliances that get them appointed to the court.

SIEGEL: Is there any judicial code of conduct that binds the Supreme Court?

TOTENBERG: There is a code of judicial conduct that applies to lower court judges. It doesn't bind Supreme Court justices because there are only nine of them or eight of them now, and you can't just stick in somebody for a given case where somebody has to recuse themselves.

But the code does say that judges should not make speeches for political candidates or publicly endorse or oppose a candidate for public office.

SIEGEL: Well...

TOTENBERG: And the Supreme Court justices try to stick to that.

SIEGEL: Well, you could argue that she did that. Now, what would happen if there were another case like Bush v. Gore, the Supreme Court case that decided the 2000 election. Could you argue Ruth Bader Ginsburg has tipped her hand on this?

TOTENBERG: I suppose you could argue it. She wouldn't be bound. And it wouldn't be the first time that this has happened. Remember that when the court was called upon to decide an important case that involved Vice President Cheney, there was a motion filed asking Justice Scalia to recuse himself because he'd gone duck hunting with Cheney. Now, Scalia didn't recuse himself, and I think that the consensus is that Ginsburg wouldn't either and that she wouldn't be obligated to.

But a number of ethics experts have worried that her comments would put the court's authority in jeopardy, that for instance if a President Trump were to ban all Muslims from immigrating and the court were to rule against Trump, it would be easier for him to flout the court's decision. I'm supposed to see Justice Ginsburg tomorrow, and I'm going to ask her these questions.